e36 M3 Evo crankshaft bearing...

[M3John]

Morning all and merry Christmas !


Just doing some random classified ad surfing and noticed the ad below :

http://www.pistonheads.com/sales/3366694.htm

What really grabbed my attention was the line :

Ad Says said:

As with all EVO's after a certain mileage, the big end bearing on the crankshaft (cylinder 6) spun in June this year. This is due to the BMW con-rod bolts relaxing over time, allowing the shell to turn. If you read the forums you will realise that this is the most common reason for Evo's being scrapped!

Now, i've had my little chariot for around nearly 8 years and covered almost 100k in it and - unless i've missed something glaringly obvious - i've never heard this before. Well certainly as a *common problem*. Has anyone on here had this issue or know much more about it. Is it something worth worrying about?

Cheers,
M3J.

[metcalp]

Yes its true we have had quite a few with this problem. arp rod bolts are very good.The E46 M3 had recalls for big end bearings and rod bolts oil pumps etc. High milage and high engine revs on track days shows the weekness.

[Pig Skill]

I wouldn't describe it as a weakness as such, more a symptom of age and the usage associated with this car.

I cant see many 100hp/l NA cars revving toward 8000rpm being >10years old and north of 100k and not inviting a spun shell. I would look into changing the bolts as suggested already with the ARP bolts. That said if OEM rod bolts have last all this time then they cant be too stretchy either.

A bit of preventative maintenance is the way forward thinks I.

[metcalp]

100 bhp per ltr is not a true figure! we had lots of evos on the rollers and the best was 318 bhp on bp super.our E30 M3 engines were 320 out of a 4 pot 2.5ltr and the best we got out of a 3.2 was 410 bhp race engines that got rebuilt after 30 hrs

[andygtt]

my M3 evo has done 165k miles... been abused on road and track and never had any engine issues despite not really looking after it properly for last 3 years.... not heard of bearing failures before so its news to me.

[TEKNOPUG]

It can happen, as can terminal vanos failure but neither are anyway near as common as forum horror stories will lead you to believe. As said, high mileage and high revs are they main cause but well cared for cars can also suffer. Just comes down to differences in design tolerances and "luck". It's worth going ARP bolts for peace of mind but it's far from inevitable that they will be required.

[leem5]

Any recommendations on where to by the bolts for the evo?

[M3John]

Thanks for the reply guys.

Reading back on what i first wrote i should have said that since i've owned the car i've put nearly 100k on the mileage and it's currently showing 155/160k.

metcalp said:

Yes its true we have had quite a few with this problem. arp rod bolts are very good.The E46 M3 had recalls for big end bearings and rod bolts oil pumps etc. High milage and high engine revs on track days shows the weekness.

Does this apply for the e36 also? I've herd about the oil pump issue on the e46.

Pig Skill said:

That said if OEM rod bolts have last all this time then they cant be too stretchy either.

Exactly what i was thinking ^
The engine in mine has never been apart and runs like a turbine !


Edited to add :

metcalp said:

100 bhp per ltr is not a true figure! we had lots of evos on the rollers and the best was 318 bhp on bp super.our E30 M3 engines were 320 out of a 4 pot 2.5ltr and the best we got out of a 3.2 was 410 bhp race engines that got rebuilt after 30 hrs

I had mine on the rollers at Surrey Rolling Road and on normal 95 octane gas Charlie managed to squeeze 317 out of the car which i thought was quite respectable. At the time he did say before the car went on the rollers that he thought i had a very healthy one.

Edited by M3John on Wednesday 28th December 06:55

[andygtt]

M3John said:

Pig Skill said:

That said if OEM rod bolts have last all this time then they cant be too stretchy either.

Exactly what i was thinking ^
The engine in mine has never been apart and runs like a turbine !

so thats 2 of us with over 160k and an original engine that runs sweet... guess this is a bit like the vanos horror stories when I bought the car, if they go its serious money, but suddenly ALL cars will suffer the same fate when in fact only a small number do.

My car hasn't been used for nearly 2 years other than go to MoT's and is just sat on my drive... just cant bring myself to sell it as its worth peanuts and is still an awsome machine on track even though the rest of the car is tired (brakes and suspension).